The Second Brain: Trust Your Gut

Leslie E. Korn

There is no doubt that nutrition affects mental health. Poor nutrition leads to and exacerbates mental illness. Optimal nutrition prevents and treats mental illness. Note the word “optimal” for nutrition to prevent and treat illness. One’s diet cannot be just “good” or provide the basics to survive; it must be nutrient dense and tailored to the needs of the individual who may have been missing the basic ingredients for optimal brain function since life in the womb.

Where there is mental illness, there is poor diet. Where there is mental illness, there is a long history of digestive problems. By adding the lens of nutrition, diet, and digestion to your clinical toolbox, you will forever change your approach to client care and enhance the efficacy of all your other methods.

The standard American diet (SAD) makes us sad! This too frequently prescribed diet consists of refined, overly processed foods containing refined sugars in fruit juices and sugary drinks, and highly refined rice, pastas, and flours used in breads and bakery goods. These processed products are loaded with chemicals and synthetic preservatives, hormones, antibiotics, and food colorings that are known to alter our mood. This type of diet is a prime contributing factor resulting in health complaints for many clients. The SAD leads to chronic inflammatory states and sets the stage for neurotransmitter imbalances. Much of it is “fake food” with dozens of chemical ingredients created in the laboratory and not on the farm or in nature. Such so-called foods are designed to survive on the shelf for months at a time—thus reducing costs to the manufacturers. The SAD diet makes us SAD because it does not provide the nutrients our brain and body need to function well. That some of us survive (though rarely thrive) on a SAD diet is just the luck of the draw, and for some people illness comes in childhood or not until middle age, but it comes invariably, just as a car without the right fuel eventually sputters to a stop.

The discovery of the “second brain,” also known as the enteric nervous system, has confirmed our experience that the “gut” communicates with our first brain. This second “brain” controls the digestive system via a complex network of over 100 million nerves and chemicals that send messages to the central nervous system, and this “brain” allows us to feel in our “guts.” When we say: “I just feel in my gut that is right,” or “my gut is telling me no,” that sensation is the second brain communicating. Feeling and sensation are part of its function, and it is linked to our emotional lives and intuition. The majority of fibers in the vagus nerve carry messages from the digestive system to the brain. The feeling of “butterflies in the stomach” describes the physiological stress we experience in the gut. This “second brain” is a term coined by Gershon (1998). It controls the breakdown and absorption of foods, elimination of waste, and the rhythms of peristalsis that move food along the digestive tract. It takes food particles and transforms them into little chemical messengers that support our emotional and cognitive life. The revolution that has occurred is that we now know that it is this second brain that makes these little messengers, the neurotransmitters, and supports bacteria that help regulate brain function.

An important discovery of the last 30 years relevant to the second brain and mental health is the endocannabinoid (eCB) system. This system figures in mental health, nutrition, and especially, in pain and the addictions. Note the middle word root “canna” and you will note it is related to the word cannabis. This system was identified as functioning in the first and second brain when scientists first began to identify the parts of the brain that responded to cannabis, or marijuana. The eCB system is involved in all aspects of mental and physical health: the microbiome and gut permeability, the stress response, appetite, obesity and eating disorders, the experience of pain (McPartland, Guy, & Di Marzo, 2014), and the “bliss states.” The neurologist Russo (2004) proposes a concept called clinical endocannabinoid deficiency syndrome, which may contribute to migraine, fibromyalgia, irritable bowel syndrome, and psychological disorders. Knowledge of this system is also central to understanding why people with schizophrenia and posttraumatic stress disorder (PTSD) may use cannabis to self-medicate, and the ways in which medical cannabis represents a growing option for less toxic medical treatments for mental illness and chronic physical diseases.

Digestion occurs in a state of relaxation. Stress can slow down or stop the digestive process. When the nervous system goes into a “freeze, fight, or flight” response, it impairs digestive muscle contractions, reduces the secretion of digestive enzymes, and redirects blood flow away from the digestive organs where it is needed and instead floods the extremities and muscles with blood, which are now poised for an emergency.

Chronic stress is also connected to allostatic load, which refers to the cumulative effects of the “wear and tear” on well-being. Allostatic load is of special importance to the second brain because the social stressors of poverty and discrimination, as well as environmental toxins, affect the ability to metabolize food, especially glucose. For example, the stress of poverty is linked to the stress of malnutrition and poor-quality nutrition on child and adult development. These stressors also include less access to quality nutrition at a time when even greater needs are placed on the mind and body for nourishment. Environmental toxins in poor urban centers are linked to higher rates of diabetes, and environmental toxins in the food supply are associated with earlier puberty in girls, which has a domino effect on risk factors like depression and sexual abuse. Incorporating socioeconomic context and the complex interplay of ethnicity and stress on mental health and nutritional status is essential to the nutritional change model I discuss throughout this book in order address affordability and health disparities.

Hormones are also an important part of the digestive process and function to regulate appetite and digestive juices. Nerves connect the brain, spinal cord, and digestive organs and release chemicals that stimulate either contraction or relaxation of the gastrointestinal (GI) tract muscles. Hunger hormones are produced and released by the stomach and small intestinal lining.

The first brain relies on the right mix of glucose and fat. If you do not consistently eat the correct combination of glucose and fats, you deprive the brain of its optimal fuel, frequently leading to hypoglycemia and ongoing cravings and hunger. Meals low in protein and fat and high in carbohydrates raise blood sugar, but they also drop sugar levels precipitously, sending the brain on a rollercoaster. These high glycemic meals impair satiety hormones and cause an increase in hunger hormones (Baum et al., 2006), which leads to overeating. These types of high-carbohydrate meals also result in fatigue. This pattern is common in people with mood lability, and they respond well to a diet low in carbs, high in animal and plant protein, and moderate in fat and vegetables. The “power lunch” refers to eating a lunch of protein and vegetables (no grains or alcohol) when negotiating an important contract or business exchange and gaining a mental edge by staying alert and awake without the sedating effects of grains and starchy carbohydrates.

Stress and Digestion
In order for digestion to function smoothly, one needs to be relaxed when eating. There is a long-time association between stress and digestive upset. This is mediated by the autonomic nervous system (ANS). Under normal circumstances the parasympathetic mode of the ANS is the autopilot that “automatically” drives the overall function of the digestive system, from the release of digestive enzymes and juices to peristalsis and elimination. In mental health we have long observed the relationship between anxiety and digestive problems. We once believed that anxiety drove the digestive problems, and thus we teach relaxation exercises that are helpful. This makes sense, as the parasympathetic system, our relaxation response, needs to be “on” for digestion to occur smoothly. However, we now know that the effect of the gut, or the digestive system, on anxiety and emotions in general is bidirectional due to the vast network of chemical messengers, the neurotransmitters that are produced in the gut.

Neurotransmitters
Neurotransmitters (NTs) are brain chemicals that communicate information throughout our brain and body. They relay signals between neurons. They affect mood, sleep, concentration, weight, carbohydrate cravings, and addictions, and they can contribute to depression, pain, anxiety, and insomnia when they are not in balance. Research continues to illuminate the ways that foods affect how NTs are made in the gut and how, in turn, this affects the brain and mind. Friendly bacteria play a role in the production of gamma-aminobutyric acid (GABA), the “antianxiety” NT illuminating the complex relationship between the brain and the gut. The gut and the brain regulate eating behavior and appetite by way of NTs. Dopamine and serotonin are the two primary neurotransmitters associated with the regulation of food intake (Bello & Hajnal, 2010; Capasso, Petrella, & Milano, 2010). For example, when people start selective serotonin reuptake inhibitors (SSRIs), or the serotonergic amino acid 5-HTP, they can become nauseated by the increase in serotonin levels in the gut. Stress impairs digestion, and poor digestion affects the neurochemicals that influence mood and well-being. Like the brain, the second brain uses over 30 NTs, and 95% of the serotonin in the body is located in the gut. High levels of serotonin are also linked with irritable bowel syndrome (Hadhazy, 2010).

Impaired digestion of protein means the amino acids are not available to the brain to support NT production, directly affecting mood, sleep, and cravings. The overuse of antibiotics, along with insufficient prebiotics in the diet to prepare the garden of the intestines to grow healthy gut microbiota, impairs the production of NTs and subsequently causes mood problems like depression and anxiety. Most antidepressants are believed to work by increasing the availability of specific neurotransmitters, but this theory is unproven; they often have side effects, lead to chemical imbalances, have limited efficacy (especially in mild to moderate depression), and become less effective over time. The theory of mood disorders as primarily based in NT imbalance is giving way to a more holistic understanding of multiple influences on mood and cognition of which NT function is only one. Indeed, the groundbreaking work by Kirsch et al. examined the role of the placebo effect on depression and suggested that there is no significant difference between antidepressant effect and placebo effect except in the severely depressed, and for the severely depressed it is “the relationship between initial severity and antidepressant efficacy [that] is attributable to decreased responsiveness to placebo among very severely depressed patients, rather than to increased responsiveness to medication” (2008, p. 266).

The use of amino acid therapy as an adjunctive or alternative method of influencing NTs, iss a natural approach to antidepressant and antianxiety medications. These pharmaceutical-grade amino acids may be compounded according to the specific biochemical needs of the individual to provide the building blocks that support specific NT production.

Essential Behavioral Steps for Relaxed Digestion

Eat in places that induce relaxation rather than places where one feels stressed.

Employ rituals such as communal eating, giving thanks, and potlucks; this can also reduce stress and improve digestion.

Breathe slowly and rhythmically before eating and during the meal.

Eat with others when possible and without the distraction of the TV or computer.

Put the fork or spoon down between bites and let it sit for 15–30 seconds or more.

Chew food 50 times or until almost liquid.

Set nutrients on the table in the kitchen organized by whether they are to be taken before the meal, during the meal, or after the meal.

Additionally, smoking, caffeine, and alcohol consumption all impair digestion and affect the stress response. Reducing or eliminating these three major stress factors should be included in goal setting early on with the client